1. Field of the Invention
The invention relates to anastomotic and blood access devices and methods, more specifically to vascular access fistulas and side-branch devices.
2. Discussion of the Related Art
In the United States alone, approximately 400,000 people have end-stage renal disease requiring chronic hemodialysis. Hemodialysis replaces kidney function by removing toxins from the blood that are normally removed by healthy kidneys. In order to remove toxins effectively, blood must be passed at a high blood flow rate through a hemodialysis machine. This high blood flow is best achieved by the creation of a permanent vascular access site that includes an arteriovenous (AV) anastomosis in which a vein is attached to an artery to form a high-flow shunt or fistula, commonly referred to as an AV fistula. AV fistulas are widely preferred for use in connection with hemodialysis vascular access based on their superior patency, low complication rates, lower cost to the healthcare system, and decreased risk of patient mortality.
In creating an AV fistula, typically, a vein is directly attached to an artery, and then six to eight weeks from the time of attachment is usually required for the fistula to sufficiently mature, i.e. to provide adequate blood flow, to be cannulated for dialysis, etc. Fistula maturation requires a compliant and responsive vasculature capable of dilating in response to the increased velocity of blood flowing into the newly created low-resistance circuit. Failure to mature of new fistulas remains a major obstacle to increasing the proportion of dialysis patients with fistulas.
In addition, waiting for a fistula to mature exposes those patients in need of more immediate dialysis to increased risk, because a less-desirable temporary access device may be employed. Typically, this temporary access device is a catheter, to be inserted for hemodialysis access until the fistula has matured. The use of a temporary catheter access exposes the patient to additional risk of bleeding and infection, as well as discomfort, and is associated with a 91% higher mortality rate compared to fistulas. In trying to increase the prevalence of fistulas in the U.S., a proportional rise in catheter use has been documented.
Moreover, some people are less than ideal candidates for a fistula. For example, if the vascular system is greatly compromised, a fistula may not be attempted because the implantation may require an invasive surgical procedure that causes trauma to vessel walls and thus, is too risky for those with a weakened vasculature. In addition, AV fistula may not be feasible in all patients due to anatomical considerations.
Accordingly, there is a need for AV fistulas exhibiting the ability to improve the maturation rates of AV fistulas, reduce the instances of AV fistula failure, and minimize the extent of vessel trauma during implantation and thereafter.